This invention relates generally to improvements in vehicle body loading and unloading mechanisms for picking up large containers of the order of vehicle bodies and for loading and unloading such containers with respect to a transport vehicle, separable therefrom. More specifically this invention relates to a hydraulic mechanism mounted on a tilting frame of a vehicle body which is capable of extending and withdrawing a cable suitable for attachment to a large container for drawing the container onto the tilting frame and onto the vehicle body.
It is often desirable to use large capacity containers for holding various types of refuse or other material and to provide for the loading and unloading of such containers with respect to a transport vehicle. Such containers can be filled when sitting on the ground, floor or other surface after which they can be picked up or loaded by power, transported to a remote point, and then set down or unloaded. It is also possible to load the body separate and apart from the motor vehicle and then transport the loaded body to a remote point and disconnect it from the vehicle while still loaded.
Vehicles of the type used herein have conventionally used cables to draw the container up onto the vehicle body. The cable is usually operated from a winch which is driven by a separate motor. By tipping the tilting frame of the vehicle body into an upward position, the container can be allowed to slide off the vehicle under the restraints of the cable and the winch. The present invention relates to the use of a hydraulic cylinder to control the operation of the cable in drawing the container onto the vehicle or allowing it to slide off of the vehicle. Similar mechanisms of this type are disclosed in U.S. Pat. Nos. 3,049,378 and 3,964,626.
Hydraulic cable units are usually either the multi cylinder type as in U.S. Pat. No. 3,049,378 wherein the cable is passed over a series of sheaves to produce movement of the cable on the order of four times the movement of the hydraulic cylinder, or the single cylinder type as in U.S. Pat. No. 3,964,626 where large movement of the cylinder is necessary to produce the cable movement required. Construction and maintenance costs are higher in the type of construction which utilizes multiple sheaves whether one or two cylinders are used.
As the cable passes around a sheave and is attached to a container, it produces a resultant force at the center of the sheave which has two vectors, one parallel to the hydraulic cylinder and one perpendicular to the hydraulic cylinder. In the prior art construction of hydraulic cable rigs, the perpendicular vector of the resultant force produces a bending movement in the hydraulic cylinder. As can be seen in FIG. 3 of U.S. Pat. No. 3,964,626, the sheave or pulley is mounted forward of the crosshead. The cable tends to rotate the pulley about the crosshead causing a sag or bending in the cylinder. The longer the cylinder, the greater the bending and the greater the stress and wear on the cylinder.
The telescopic hydraulic cylinder in its extended position is, in the prior art, not extremely resistant to vertical and horizontal vibrations caused by rough roads and general vibration during travel. Typically, the pressure of the cylinder will hold the cylinder fully extended and square against the internal stop rings of the cylinder. However, if this pressure is relieved for some reason, the cylinder may vibrate during travel which leads to a shorter cylinder life. In the present invention cylinder vibration is reduced by means of lugs attached to the cylinder and supports or stops attached to a crossplate extending widthwise across the tilting frame. When the hydraulic cylinder is fully extended, the lugs rest on, or reside slightly above, the supports or stops.
Also, in the present invention, the bending on the cylinder is eliminated and the cylinder is readily removable from the frame of the vehicle. Removal of the cylinder for repair or overhaul purposes is usually a difficult time consuming task. The present invention facilitates the removal of the cylinder by merely removing one pin connection and sliding the cylinder and crossheads out of the crosshead guides.